Semiconductor structure and method for manufacturing thereof

ABSTRACT

A semiconductor structure and method for manufacturing thereof are provided. The semiconductor structure includes a silicon substrate having a first surface, a III-V layer on the first surface of the silicon substrate and over a first active region, and an isolation region in a portion of the III-V layer extended beyond the first active region. The first active region is in proximal to the first surface. The method includes the following operations. A silicon substrate having a first device region and a second device region is provided, a first active region is defined in the first device region, a III-V layer is formed on the silicon substrate, an isolation region is defined across a material interface in the layer by an implantation operation, and an interconnect penetrating through the isolation region is formed.

CROSS REFERENCE TO RELATED APPLICATIONS

Present application is a divisional of U.S. application Ser. No.16/433,775, filed on Jun. 6 2019, which is a continuation of U.S.application Ser. No. 15/460,894, filed on Mar. 16, 2017, which is adivisional of U.S. application Ser. No. 14/928,623, filed on Oct. 30,2015. All of the above-referenced applications are hereby incorporatedherein by reference in their entirety.

BACKGROUND

Recently, the development of power electronic devices such as switchesor rectifiers highlights manufacturing of power devices. Typically,power devices are made of III-V material. By means of semiconductormanufacturing, power devices are able to be integrated into anintegrated circuit or a chip. in this way, power devices have morecompact size and versatility.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a diagram of a semiconductor structure, in accordance withsome embodiments of the present disclosure.

FIG. 2 is a diagram of a semiconductor structure, in accordance withsome embodiments of the present disclosure.

FIG. 3 is a cross section of a semiconductor structure, in accordancewith some embodiments of the present disclosure.

FIG. 4 is a diagram of a semiconductor structure, in accordance withsome embodiments of the present disclosure.

FIGS. 5A to 5G are diagrams showing a method of manufacturing asemiconductor device, in accordance with some embodiments of the presentdisclosure.

FIG. 6 is a flow diagram illustrating a method of forming asemiconductor structure, in accordance with some embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to he limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

FIG. 1 is a diagram of a semiconductor structure 10, in accordance withsome embodiments of the present disclosure. Referring to FIG. 1, thesemiconductor structure 10 includes a first device 11 and a seconddevice 12. The first device 11 and the second device 12 have a firstsurface 110 and a second surface 120, respectively. The first surface110 is co-planar with the second surface 120.

In some embodiments, the first device 11 is a Si active device, such astransistors, diodes, photo-diodes, fuses, resistors, capacitors, etc.For example, the transistors include metal-oxide-semiconductor (MOS)transistors, bipolar junction transistors (BJTs), complementary MOS(CMOS) transistors, etc. Moreover, the first device 11 may include logicdevice, memory device (for example, a static random access memory(SRAM)), radio frequency (RF) device, input/output (I/O) device,system-on-chip (SoC) device, other suitable types of devices, orcombinations thereof.

In some embodiments, the second device 12 is high-voltage devices orpower devices, which are commonly used as switches or rectifiers inpower electronic circuits or in integrated circuits. For example, somecommon power devices are the power diode, thyristor, powermetal-oxide-semiconductor field-effect transistor (MOSFET), bipolarjunction transistor (BJT) and insulated gate bipolar transistor (IGBT).A power diode or MOSFET operates on similar principles to its low-powercounterpart, but is able to carry a larger amount of current andtypically is able to support a larger reverse-bias voltage in theoff-state.

The first device 11 includes a first active region 112. The first activeregion 112 is located in a first device region 14A of a substrate 14.The first device region 14A is a portion of the substrate 14 associatedwith the first device 11. The substrate 14 and the first active region112 are made of a first material system. In some embodiments, thesubstrate 14 and the first active region 112 are made of silicon.Moreover, the first device 11 includes a first region 13A of a layer 13over the first device region 14A. The layer 13 is made of a secondmaterial system different from the first material system. For example,the layer 13 is made of II-V material, which may be gallium arsenide,indium arsenide, indium gallium arsenide, indium phosphide, galliumnitride, indium antimonide, gallium antimonide, gallium phosphide,and/or any ternary or quaternary compounds thereof or mixtures or alloysthereof.

In some embodiments, the substrate 14 includes silicon germanium,gallium arsenic, silicon carbon, or other suitable semiconductormaterials. In some embodiments, the substrate 14 further includes dopedregions such as a P-well and/or an N-well (not shown). In some otherembodiments, the substrate 14 further includes other features such as aburied layer, and/or an epitaxy layer. Furthermore, in some embodiments,the substrate 14 is semiconductor on insulator such as silicon oninsulator (SOI), in other embodiments, the semiconductor substrate 14includes a doped epi layer, a gradient semiconductor layer, and/orfurther includes a semiconductor layer overlying another semiconductorlayer of a different type such as a silicon layer on a silicon germaniumlayer. In some other examples, a compound semiconductor substrateincludes a multilayer silicon structure or a silicon substrate mayinclude a multilayer compound semiconductor structure. In someembodiments, the substrate 14 may include other elementarysemiconductors such as germanium and diamond. In some embodiments, thesubstrate 14 includes a compound semiconductor such as, silicon carbide,gallium arsenide, indium arsenide, or indium phosphide.

Similarly, the second device 12 includes a second active region 122 in asecond region 13B of the layer 13. The second active region 122 iscomposed of second material system. In some embodiments, the secondactive region 122 is not overlapping with the first active region 112 inthe first device region 14A. The second active region 122 has a side 123indicated by a dotted line 132. The side 123 of the second active region122 acts as a border between the first device 11 and the second device12. Moreover, the second device 12 further includes a second deviceregion 14B of the substrate 14. The second device region 14B of thesubstrate 14 is associated with the second device 12. The second deviceregion 14B is below the second active region 122.

In some embodiments, the first surface 110 and the second surface 120form a coplanar surface which is the surface of the layer 13. That is,there is substantially no step difference between the first surface 110and the second surface 120. In the present embodiment, the first device11 and the second device 12 are immediately adjacent to each other. Thesemiconductor structure 10 becomes more compact, and therefore thesemiconductor structure 10 has relatively low area cost. Moreover, thefirst device 11 and the second device 12 are integrated withoutundergoing any bonding operation. In addition, no step differencebetween the first surface 110 and the second surface 120 furtherfacilitates the subsequent metallization operations where the quality ofthe photolithography is highly depending on the height uniformity of theprojected surface,

In some existing semiconductor structures integrating III-V materialsystem and Si material system, the two material systems are connected bya bonding operation, for example, the Si material system stacks on theIII-V material system. The bonding operation leads to relative highcost. Moreover, due to the bonding operation, there is typically a stepdifference between a surface of the III-V material system and a surfaceof the Si material system. The region in proximity to the stepdifference cannot be implemented with any active device and thus apredetermined device region is wasted. Accordingly, such semiconductorstructure having a step difference between integrated devices consumemore area, and therefore have relatively high area cost.

FIG. 2 is a diagram of a semiconductor structure 20. in accordance withsome embodiments of the present disclosure. Referring to FIG. 2, thesemiconductor structure 20 is similar to the semiconductor structure 10described and illustrated with reference to FIG. 1 except that thesemiconductor structure 20 includes an isolation region 27 in the firstdevice 21.

The isolation region 27 is in the first region 13A of the layer 13 ofthe second material system and over the first active region 112. Theisolation region 27 is configured to repel carriers of the second activeregion 122 from entering the first region 13A of the layer 13 in thefirst device 21. The isolation region 27 has a first side 271 and asecond side 272 opposite to the first side 271. The first side 271overlaps with the side 123 of the second active region 122, and is usedto determine the border between the first device 11 and the seconddevice 12. If the first side 271 of the isolation region 27 extendstoward a side 124 of the second active region 122, the scale of thesecond device 12 decreases and the scale of the first device 11increases, and vice versa.

Moreover, the first active region 112 has a first side 113 and a secondside 114 opposite to the first side 113. In the present embodiments, afirst distance W1 between the first side 271 and the second side 272 ofthe isolation region 27 is greater than a second distance W2 between thefirst side 113 and the second side 114 of the first active region 112.In some embodiments, difference between the first distance W1 and thesecond distance W2 is less than 10 μm.

For similar reasons as provided in the embodiment of FIG. 1, since thefirst surface 110 of the first device 21 is coplanar with the secondsurface 120 of the second device 12, the area cost relatively low andmanufacturing of the semiconductor structure 20 becomes simpler due tono requirement of the bonding operation.

FIG. 3 is a cross section of a semiconductor structure 30, in accordancewith some embodiments of the present disclosure. Referring to FIG. 3,the semiconductor structure 30 is similar to the semiconductor structure20 described and illustrated with reference to FIG. 2 except that thesemiconductor structure 30 includes more details of a first device 31and a second device 32.

The first device 31 and the second device 32 are similar to the firstdevice 21 and the second device 12, respectively, described andillustrated with reference to FIG. 2 except that the first device 31includes a first active region 312 with two doped regions 314 and 316therein, the second device 32 includes a second active region 322, andthe first device 31 and the second device 32 include a layer of thesecond material system. The second material system has a first bandgaplayer 36 and a second bandgap layer 38.

The first active region 312 and two doped regions 314 and 316 define anactive device, such as a transistor. For example, the active region 312is doped with a dopant of p-type and the doped regions 314 and 316 aredoped with a dopant of n-type. In such a manner, the first active region312 and the doped regions 314 and 316 define n-type semiconductordevices, such as n-channel metal-oxide-semiconductor field effecttransistors (MOSFETs). Alternatively, for example, the first activeregion 312 is doped with a dopant of n-type and the doped regions 314and 316 are doped with a dopant of p-type. In such a manner, the firstactive region 312 and the doped regions 314 and 316 define p-typesemiconductor devices, such as p-channel metal-oxide-semiconductor fieldeffect transistors (MOSFETs). The active device is communicativelycoupled to another device via an interconnect 37 and a patternedconductive layer 35 on the second bandgap layer 38 of the secondmaterial system. For example, the interconnect 37 is a thorough-GaN-Via(TGV), and the patterned conductive layer 35 is a first metal layerafter the front end operations. The interconnect 37 penetrates throughthe layer including the first bandgap layer 36 and the second bandgaplayer 38, and is configured to connect the patterned conductive layer 35at one end and the first active region 312 at the other end.

The first bandgap layer 36 and the second bandgap layer 38 are made ofthe second material system. In some embodiments, second bandgap isgreater than the first bandgap. In the present embodiment, the firstbandgap layer 36 is GaN and the second bandgap layer 38 is AlGaN whilethe disclosure is not limited thereto. The first bandgap layer 36 andthe second bandgap layer 38 may be gallium arsenide, indium arsenide,indium gallium arsenide, indium phosphide, gallium nitride, indiumantimonide, gallium antimonide, gallium phosphide, and/or any ternary orquaternary compounds thereof or mixtures or alloys thereof.

Moreover, the first device 31 includes a first portion 36A of the firstbandgap layer 36 and a first portion 38A of the second bandgap layer 38.The first portion 36A and the first portion 38A are associated with thefirst device 31. The first portion 36A of the first bandgap layer 36 ison the first device region 14A of the substrate 14. The first portion38A of the second bandgap layer 38 is on the first portion 36A of thefirst bandgap layer 36.

The isolation region 27 is over the first device region 14A and acrossan interface between the first portion 36A of the first bandgap layer 36and the second portion 38A of the second bandgap layer 38. In this way,for similar reasons as provided in the embodiment of FIG. 2,two-dimensional electron gas (2-DEG) generated in the second device 32does not flow into any portion of the first device 31 due tonegatively-charged ions repelling electrons coming from the secondactive region 322 of the second device 32.

On the other hand, the second device 32 includes a second portion 3613of the first bandgap layer 36 and a second portion 38B of the secondbandgap layer 38. The second portion 36B and the second portion 38B areassociated with the second device 32. The second portion 36B of thefirst bandgap layer 36 is on the second device region 14B of thesubstrate 14. The second portion 38B of the second bandgap layer 38 ison the second portion 36B of the first bandgap layer 36.

The second active region 322 is defined by the first bandgap layer 36and the second bandgap layer 38. Since bandgap of the second bandgaplayer 38 is greater than that of the first bandgap layer 36, a band gapdiscontinuity exists between the first bandgap layer 36 and the secondbandgap layer 38. The electrons from a piezoelectric effect in thesecond bandgap layer 38 drop into the first bandgap layer 36, resultingin a very thin layer (i.e. the second active region 322) of highlymobile conducting electrons in the first bandgap layer 36. The thinlayer of 2-DEG is located at the interface between the first bandgaplayer 36 and the second bandgap layer 38. Thus, the carrier channel hashigh electron mobility because the first bandgap layer 36 is un-doped orunintentionally doped, and the electrons can move freely withoutcollision or substantially reduced collision with the impurities. It isnoted that for clarity of illustration, dimension of the second activeregion 322 is exaggerated.

For communication with another device, such as the active device of thefirst device 31, there is also the conductive patterned layer 35 on thesecond portion 38B of the second bandgap layer 38, and that conductedpatterned layer 35 is coupled to the second active region 322, andfurther coupled to drain, gate and source of a transistor if the secondportion 36B of the second bandgap layer 36 and the second portion 38B ofthe second bandgap layer 38 define transistors.

In the present embodiment, the first surface 110 and the second surface120 are a surface of the second bandgap layer 38. Therefore, the firstsurface 110 is coplanar with the second surface 120. For similar reasonsas provided in the embodiment of FIG. 1, since the first surface 110 ofthe first device 31 is coplanar with the second surface 120 of thesecond device 32, the cost per area is relatively low and manufacturingof the semiconductor structure 30 becomes simpler due to no requirementof the bonding operation.

FIG. 4 is a cross section of a semiconductor structure 40, in accordancewith some embodiments of the present disclosure. Referring to FIG. 4,the semiconductor structure 40 is similar to the semiconductor structure30 described and illustrated with reference to FIG. 3 except that thesemiconductor structure 40 includes a different first device 41.

The first device 41 is similar to the first device 31 described andillustrated with reference to FIG, 3 except that the first device 41includes a first active region 412 with a doped region 414 in the firstdevice region 14A of the substrate 14. The first active region 412 andthe doped region 414 define a zener diode (or a rectifier). The dopedregion 414 serves as an anode of the zener diode and the first activeregion servers as a cathode of the zener diode. The interconnect 37penetrates through the first bandgap layer 36 and the second bandgaplayer 38, and is configured to connect the doped region 414 and thefirst active region 412 at one end and the patterned conductive layer 35at the other end.

For similar reasons as provided in the embodiment of FIG. 1, since thefirst surface 110 of the first device 41 is coplanar with the secondsurface 120 of the second device 32, the cost per area is relatively lowand manufacturing of the semiconductor structure 40 becomes simpler dueto no requirement of the bonding operation.

FIGS. 5A to 5G are diagrams showing a method of manufacturing asemiconductor structure, in accordance with some embodiments. Referringto FIG. 5A, a substrate 502 is provided. The substrate 502 includes afirst device region 502A and a second device region 502B. The firstdevice region 502A and the second device region 502B are associated witha first device and a second device of the semiconductor structure,respectively. In some embodiments, the substrate 502 includes a p-typesubstrate.

Referring to FIG. 5B, a first active region 504 is formed in thesubstrate 502 by, for example, an ion implantation operation. In someembodiments, the first active region 504 is doped with a dopant ofn-type. In other embodiments, the first active region 504 is doped witha dopant of p-type.

Referring to FIG. 5C, doped regions 506 are formed in the first activeregion 504 by, for example, an ion implantation operation followed by anannealing operation. In some embodiments, the doped regions 506 aredoped with a dopant of n -type. In other embodiments, the doped regions506 are doped with a dopant of p-type. With the first active region 504of n-type dopant and the doped regions 506 of p-type dopant, a PMOStransistor is formed in the substrate 502. Contrarily, with the firstactive region 504 of p-type dopant and the doped regions 506 of n-typedopant, an NMOS transistor is formed in the substrate 502. The dopedregions 506 serve as drain or source of the NMOS transistor or the PMOStransistor.

Referring to FIG. 5D, a first bandgap layer 508 is formed on thesubstrate 502 by, for example, a deposition operation. In addition, asecond bandgap layer 510 is formed on the first bandgap layer 508 by,for example, a deposition operation. Bandgap of the second bandgap layer510 is greater than that of the first bandgap layer 508. For example,the first bandgap layer 508 is made of a material of GaN, and the secondbandgap layer 510 is made of a material of AlGaN.

Referring to FIG. 5E, an isolation region 512 is formed in the firstbandgap layer 508 and the second bandgap layer 510 by, for example, a animplantation operation, implanting negatively-charged ions in an exposedsecond bandgap layer 510 associated with the first device region 502A.Specifically, the isolation region 512 across an interface between thefirst bandgap layer 508 and the second bandgap layer 510 associated withthe first device region.

Referring to FIG. 5F, an interconnect 514 is formed in the first bandgaplayer 508 and the second bandgap layer 510 by, for example, an etchingoperation, forming a via trench exposing the doped regions 506 and aportion of the first active region 504, and followed by a depositionoperation, depositing conductive materials in the via trench to form theinterconnect 514. For example, the interconnect 514 is athorough-GaN-Via (TGV). A transistor defined by the first active region504 and the doped regions 506 is communicatively coupled to anotherdevice via an interconnect 514.

Referring to FIG. 5G, a patterned conductive layer 516 is formed on thesecond bandgap layer 510 by, for example, a deposition operation,followed by an etching operation. Note the patterned conductive layer516 can be positioned on both the first device region 502A and thesecond device region 502B. In some embodiments, the patterned conductivelayer 516 is a first metal layer after the front end operations.

in the present embodiment, a surface of the semiconductor structure is asurface of the second bandgap layer 510. Therefore, a surface of thefirst device referring to a device at a right side of the dotted lineand whose active region is defined by a first material system) iscoplanar with a surface of the second device (referring to a device at aleft side of the dotted line and whose active region is defined by thesecond material system). For similar reasons as provided in theembodiment of FIG. 1, the cost per area of the semiconductor structureis relatively low and manufacturing of the semiconductor structurebecomes simpler due to no requirement of the bonding operation.

FIG. 6 is a flow diagram illustrating a method of forming asemiconductor structure, in accordance with some embodiments of thepresent disclosure. Referring to FIG. 6, in operation 600, a substrateof a first material system is provided. The substrate includes a firstdevice region and a second device region. The first device region andthe second device region are associated with a first device and a seconddevice, respectively. The substrate is similar to the substrate 14 orthe substrate 502 described and illustrated with reference to FIGS. 4and 5A, respectively. In addition, the first device region and thesecond device region are similar to the first device region 14A and thesecond device region 14B illustrated and described with reference toFIG. 3. In an embodiment, the substrate is a p-type substrate.

In operation 602, a first active region is defined in the first deviceregion, and then doped regions are defined in the first active region,in an embodiment, the first active region is an n-well and the dopedregions include a p-type dopant, resulting in a PMOS transistor. Inanother embodiment, the first active region is a p-well, and the dopedregions include an n-type dopant.

In operation 604, a first bandgap layer of a second material system isformed on the substrate. The first bandgap layer is similar to the firstbandgap layer 36 described and illustrated with reference to FIG, 3. Thesecond material system is different from the first material system. Forexample, the first material system includes silicon while the secondmaterial system includes a III-V material, which may be galliumarsenide, indium arsenide, indium gallium arsenide, indium phosphide,gallium nitride, indium antimonide, gallium antimonide, galliumphosphide, and/or any ternary or quaternary compounds thereof ormixtures or alloys thereof. In the present embodiment, the first bandgaplayer is a GaN layer.

In operation 606, a second bandgap layer of the second material systemis formed on the first bandgap layer. The second band gap layer issimilar to the second bandgap layer 38 described and illustrated withreference to FIG. 3. Bandgap of the second bandgap layer is greater thanthat of the first band gap layer. In such a manner, a second activeregion is defined by an interface of the first bandgap layer and thesecond bandgap layer. In the present embodiment, the second bandgaplayer is an AlGaN layer.

Subsequent to operation 606, in operation 608, an isolation region isdefined at an interface between the first bandgap layer and the secondbandgap layer. The isolation region is similar to the isolation region27 described and illustrated with reference to FIG. 3. For similarreasons as provided in the embodiment of FIG. 2, the isolation region isconfigured to repel electrons coming from the second active region ofthe second device region 502B.

In operation 610, an interconnect is formed. The interconnect penetratesthrough the first bandgap layer and the second bandgap layer at thefirst device region 502A, and connects the first active region at oneend, a conductive layer discussed later at the other end.

In operation 612, a patterned conductive layer is formed on the secondbandgap layer and in connection with the interconnect. The patternedconductive layer is electrically coupled to the first active region viathe interconnect.

Some embodiments have one or a combination of the following featuresand/or advantages. In some embodiments, a semiconductor structureincludes a first device having a first surface and a second devicehaving a second surface. The second surface is coplanar with the firstsurface. The first device includes a first active region defined by afirst material system. The second device includes a second active regiondefined by a second material system. The second material system isdifferent from the first material system.

In some embodiments, a semiconductor structure includes a siliconsubstrate and a layer. The silicon substrate has an active regiontherein. The III-V layer is on the substrate and over the active regionof the silicon substrate.

In some embodiments, a method for manufacturing a semiconductorstructure includes at least the following operations. A substrate of afirst material system is provided. The substrate has a first deviceregion and a second device region. An active region in the first deviceregion is defined. A layer of a second material system is formed on thesubstrate. The second material system is different from the firstmaterial system. An isolation region is defined in a portion of thelayer over the first device region.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother operations and structures for carrying out the same purposesand/or achieving the same advantages of the embodiments introducedherein. Those skilled in the art should also realize that suchequivalent constructions do not depart from the spirit and scope of thepresent disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method for manufacturing a semiconductorstructure, comprising: providing a silicon substrate having a firstdevice region and a second device region; defining a first active regionin the first device region; defining a doped region in proximal to afirst surface of the silicon substrate, wherein the first active regionand the doped region include dopants of different polarities; forming aIII-V layer on the first surface of the silicon substrate after thedefining the first active region, wherein the layer is closer to thefirst surface than to a second surface opposite to the first surface ofthe silicon substrate; and defining an isolation region in the layer byan implantation operation.
 2. The method of claim 1, wherein theisolation region is formed to extend across the first device region. 3.The method of claim 1, wherein the first active region extends from thefirst surface of the silicon substrate and the doped regions formed inthe first device region.
 4. The method of claim 1, further comprising:forming an interconnect penetrating through the isolation region.
 5. Themethod of claim 4, wherein the forming the interconnect comprises:forming a plurality of trenches in the III-V layer and exposing thefirst device region after defining the isolation region.
 6. The methodof claim 1, further comprising forming a patterned conductive layer onthe III-V layer after forming the interconnect.
 7. The method of claim6, wherein the patterned conductive layer is formed over the firstdevice region and the second device region.
 8. The method of claim 1,further comprising: defining a second active region in the III-V layerover the second device region and partially leveled with the isolationregion.
 9. A method for manufacturing a semiconductor structure,comprising: providing a silicon substrate having a first device regionand a second device region; forming a III-V layer on the siliconsubstrate laterally covering the first device region and the seconddevice region; forming an ion implanted region in the III-V layer overthe first device region, and the ion implanted region includesnegatively-charged ions; and forming an interconnect penetrating the ionimplanted region.
 10. The method of claim 9, further comprising:defining a first active region in the first device region prior to theforming the III-V layer.
 11. The method of claim 10, wherein the ionimplanted region overlaps an entirety of the first active region. 12.The method of claim 9, wherein the forming the III-V layer comprises:forming a first III-V sub-layer on the silicon substrate; and forming asecond III-V sub-layer on the first III-V sub-layer, wherein a bandgapof the second III-V sub-layer is greater than that of the first III-Vsub-layer.
 13. The method of claim 12, wherein a second active region isdefined by an interface of the first III-V sub-layer and the secondIII-V sub-layer over the second device region.
 14. The method of claim13, wherein an interface between the second active region and the ionimplanted region is aligned to an interface between the first deviceregion and the second device region.
 15. The method of claim 12, whereinthe ion implanted region extends across an interface between the firstIII-V sub-layer and the second III-V sub-layer.
 16. A method formanufacturing a semiconductor structure, comprising: providing a siliconsubstrate having a first surface, a first device region and a seconddevice region; performing a first implantation on a first surface of esilicon substrate in the first device region; forming a first bandgaplayer on the first surface of the silicon substrate; forming a secondbandgap layer on the first bandgap layer; and performing a secondimplantation on the second bandgap layer over the second. device regionto form an ion implanted region, wherein a lateral side of the ionimplanted region defines a border between the first device region andthe second device region.
 17. The method of claim 16, furthercomprising: performing a third implantation on the first surface of thesilicon substrate after the first implantation, wherein a dopant of thethird implantation has a polarity different from that of the firstimplantation.
 18. The method of claim 16, wherein a thickness of the ionimplanted region from a top surface of the second bandgap layer isgreater than a thickness of the second bandgap layer.
 19. The method ofclaim 16, further comprising: forming a trench penetrating the firstbandgap layer and the second bandgap layer; and depositing a conductivematerial in the trench.
 20. The method of claim 16, further comprising:forming a plurality of conductive segments in the first device regionand the second device region, wherein at least one of the conductivesegments in the first device region is electrically connected to anactive region formed by the first implantation.